A torque fluctuation absorber, for example for a hybrid vehicle, is equipped on a power transmission path between an engine and a motor generator (or a transmission), and absorbs (or buffers) fluctuation torque generated between the engine and the motor generator (or the transmission). A type of torque fluctuation absorber includes a damper portion, which absorbs the fluctuation torque by elastic force, and a hysteresis portion, which absorbs (or buffers) fluctuation by hysteresis torque by, for example, friction (see JP2002-13547A and JP2003-194095). The aforementioned type of torque fluctuation absorber provides a low torsional rigidity for a low torque range as a torsional characteristic at the damper portion to avoid generating resonance when an engine speed is low.
With the above torsional characteristic at the damper portion, a driver loses drivability by sensing a discomfort due to a large torsional rigidity difference at a transition from the low torque range to a high torque range.
A need thus exists for a clutch cover assembly, which is not susceptible to the drawback mentioned above.